Flash Flood Guidance
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AWUS01 KWNH 130221
FFGMPD
TXZ000-OKZ000-KSZ000-130819-
Mesoscale Precipitation Discussion 1267
NWS Weather Prediction Center College Park MD
1020 PM EDT Sat Sep 12 2026
Areas affected...near the OK/KS border
Concerning...Heavy rainfall...Flash flooding possible
Valid 130219Z - 130819Z
Summary...Showers and thunderstorms are capable of hourly rain
amounts to 2.5" with local totals to 4" during the next six hours.
Flash flooding is possible on a widely scattered basis.
Discussion...Showers and thunderstorms with very cold cloud tops
on infrared satellite imagery near the KS/OK border are elevated
over a surface front which angles through OK near a zone of 850
hPa confluence/convergence. From the central OK/KS border
eastward, the atmosphere is relatively uncapped with 700 hPa
temperatures near or below 12C. Precipitable water values are
1.75-2". MU CAPE is 2000-3500 J/kg. Effective bulk shear is
30-40 kts.
The 18z HREF/12z REFS are a few hours behind on the convective
evolution here and not terribly helpful...used the 00z hi-res
NAM/00z ARW/00z ARW2 and recent radar reflectivity trends as a
starting point for convective placement during the next six hours.
When adjusting for the three hour offset -- the signal in the 12z
REFS/18z HREF is never better for heavy rainfall than it is right
now. However, there are aspects of the environment which improve
with time, such as the low-level inflow increasing while it veers.
The 18z-based Galvez-Davison Index implies an increase in
convective coverage with time across portions of southern KS and
OK. Hourly rain amounts to 2.5" with additional local totals to
4" are possible where storms backbuild, train, or merge. Flash
flood occurrences could be widely scattered, weighted towards
urban areas given the moderate to high three hourly flash flood
guidance values.
Roth
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...AMA...DDC...ICT...OUN...TSA...
ATTN...RFC...TUA...NWC...
LAT...LON 37629825 37609705 36859539 35669572 35519764
35680069 36949942